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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 601. |
Which of the following statement is `//`are correct regarding `F^(-)` and `CI^(-)` (i) `Cl^(-)` can give up an electron more easily than `F^(-)` (ii) `Cl^(-)` is smaller in size than `F^(-)` (iii) `Cl^(-)` is a better reducing agent then `F^(-)` (iv) `F^(-)` can be oxidized more readily than `Cl^(-)`A. (1) and (i)B. (i) and (iii)C. (i),(ii) and (iv)D. (ii) and (iv) |
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Answer» Correct Answer - 1 `2Cl^(-)+F_(2)rarr2F^(-)+Cl_(2)` `CI^(-)` ion can give up an electron more easily than `F^(-)` because `E_(Cl_(2)//Cl^(-))^(Ɵ) lt E_(F_(2)//F^(-))^(Ɵ)` |
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| 602. |
`BF_(3)+Hfto` |
| Answer» Correct Answer - `H^(+)[BF_(4)]^(-)` | |
| 603. |
A gas (X) is obtained when copper reacts with dilute `HNO_(3)`. The gas thus formed reacts with oxygen to give brown fumes of (Y). (Y) when dissolved in water gives an important acid (Z) and the gas (X). X, Y and Z respectively areA. `NO, NO_(2), HNO_(3)`B. `NO_(2), NO, HNO_(3)`C. `N_(2)O, NO, HNO_(2)`D. `NO, N_(2)O, HNO_(3)` |
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Answer» Correct Answer - A `3Cu+8HNO_(3("dil"))rarr3Cu(NO_(3))_(2)+underset("(X)")(2NO)+4H_(2)O` `2NO+O_(2) hArr underset("(Y)")(2NO_(2))` `underset("(Y)")3NO_(2)+H_(2)Orarrunderset("(Z)")(2HNO_(3))+underset("(X)")(NO)` |
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| 604. |
Which of the following is incorrect regarding concentrated nitric acid?A. Sulphur is oxidised by conc. `HNO_(3)` to sulphuric acidB. Carbon on treatment with conc. `HNO_(3)` yields `NO_(2)+CO_(2)+H_(2)O`C. Phosphorus reacts with conc. `HNO_(3)` to yield orthophosphoric acidD. Iodine is oxidized by conc. `HNO_(3)` to periodic acid |
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Answer» Correct Answer - 4 Nitric acid is a powerful oxidizing agent.Teh concentrated acid behaves thsu with reducing agents: `2HNO_(3)rarrH_(2)O+2NO_(2)+O` `S+6HNO_(3)rarrH_(2)SO_(4)+2H_(2)O+6NO_(2)` `C+4NHO_(3)rarrCO_(2)+2H_(2)O+4NO_(2)` `P+5HNO_(3)rarrH_(3)PO_(4)+H_(2)O+5NO_(2)` `I_(2)+10HNO_(3)rarr2HIO_(3)+4H_(2)O+10NO_(2)` |
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| 605. |
Iron reacts with very dilute nitric acid to produceA. `NH_(4)NO_(3)`B. `N_(2)O`C. `NO`D. `NO_(2)` |
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Answer» Correct Answer - 1 `Fe` forms ammonium nitriate with very dilute nitric acid: `4Fe+10HNO_(3)rarr4Fe(NO_(3))_(2)+NH_(4)NO_(3)+3H_(2)O` it forms nitrous oxide with dilute nitric acid: `4Fe+10HNO_(3) rarr4Fe (NO_(3))_(2)+N_(2)O+5H_(2)O` With concentrated nitric acid it forms nitrogen dioxide `Fe+6HNO_(3)rarrFe(NO_(3))_(3)+3NO_(2)+3H_(2)O` |
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| 606. |
Aluminium widely occurs in nature asA. cryoliteB. bauxiteC. feldsparsD. all of these |
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Answer» Correct Answer - D Cryolite is `Na_(3)AlF_(6)` (sodium aluminum fluoride), bauxite is `Al_(2)O_(3) . 2H_(2)O`, and feldspar is `K_(2)O . Al_(2)O_(3) . 6SiO_(2)`. |
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| 607. |
At elevated temperaturesA. `N_(2)`becomes increasingly reactiveB. `N_(2)`reacts with some of the transition metalsC. `N_(2)`reacts directly with elements of group `2, 13, 14` and with `H_(2)`D. all the above are true |
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Answer» Correct Answer - 4 Nitrogen consists of diatomic moleules, `N_(2)` which are extraordinary stable, not undergoing any appreciable dissociation below `3000^(@)C`. This explains the inertness of `N_(2)` which only conbines with other elements when heated. Although `N_(2)` is rather inert,it will Combine with ` H_(2)` under pressure in the oresence of a catalyst to form ammonis and with oxygen ,when sparked to give nitrogen oxide. The former reaction is of immense industrial importance while the latter reaction takes place int he atmosphere during lighning flashes. It will also combine with some other non-metals (like `B`and `Si` to give covalent nitrides. Lithium and the group `2` metals combine directly with nitrogen under the right conditions to give ionic nitrides .Some transition metals also combine with the gas at red heat, if they arefinely divided to from interstitial nitrides. |
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| 608. |
Correct order of electronegativity of group 15A. NgtPgtAsgtSbB. SbgtAsgtPgtNC. NgtAsgtPgtSbD. NgtAsgtSbgtP |
| Answer» Correct Answer - A | |
| 609. |
Which set of elements have strongest tendency to form anions ? |
| Answer» Iodine has a tendency to form cation `(I^(+)` ion). | |
| 610. |
Maximum covalent character is shown byA. `NCl_(3)`B. `PCl_(3)`C. `AsCl_(3)`D. `SbCl_(3)` |
| Answer» Correct Answer - A | |
| 611. |
Which of the following elements always forms covalent bonds?A. `Pb`B. `Si`C. `Al`D. `B` |
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Answer» Correct Answer - D Because the sum of the first three ionization enthalpies for `B` is so high that it cannot be compensated in the form of lattice enthalpy or hydration enthalpy. Moreover, the hypothetical `B^(3+)` ion will have very high charge density resulting in high polarization of the anion. |
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| 612. |
Assertion : Compounds formed between non-metals are largely covalent in character. Reason : Non-metals readily form anions |
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Answer» Correct Answer - B compounds formed between non-metals are largely covalent in character because of small differences in their electronegatives. |
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| 613. |
Which one of the following elements of group 13 can react with alkali solutions to give `H_(2)` gas?A. Boron compounds have three covalent bonds hence, require two electrons to complete octet hence, electron deficient compounds.B. AluminiumC. GalliumD. All of these |
| Answer» Correct Answer - D | |
| 614. |
Elements of group 13 mainly form covalent compounds becauseA. Size of ions is smallB. Sum of three ionisation energies is very highC. Electronegativity values are highD. All of these |
| Answer» Correct Answer - D | |
| 615. |
General oxidation state shown by group 13 elements isA. `+1 and +3`B. `+1,+2 and +3`C. `+2,+3 and +4`D. `+1 and +4` |
| Answer» Correct Answer - A | |
| 616. |
Give reasons : (i) `PCl_(5)` is more volatile than `PCl_(3)`. (ii) O-O bond has lower bond dissociation enthalpy than S-S bond. (iii) `F_(2)` is stronger oxidising than `Cl_(2)`. |
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Answer» (i) In `PCl_(5)` molecule, P atom is present in higher oxidation state `(+5)` than in `PCl_(3)` molecule in which P atom is in `(+3)` oxidation state. Therefore, `PCl_(5)` is more easily hydrolysed in coming into contact with water and is also more volatile than `PCl_(3)`. (ii) Due to smaller bond length of `( : overset(* *)O=overset(* *)O: )` the interelectronic repulsion is more than in ` : underset(* *) overset(* *)S-underset( * *)overset(* *)S : ` bond in which bond length is comparatively more. (iii) Since `E^(@)` value of `F_(2)(2.87 V)` is more than that of `Cl_(2) (E^(@)=1.36 V)`, it can act as a stronger oxidising agent than `Cl_(2)`. |
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| 617. |
Which of the following statements are correct ?A. Fullerences have dangling bondsB. Fullerences are cage-like moleculesC. Graphite is thermodynamically most stable allotrope of carbonD. Graphite is slippery and hard and therefore used as a dry lubricant in machines. |
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Answer» Correct Answer - B::C Fullerence an allotrope of carbon with finite number of carbon atoms with closed cage structure has been identified. The `C_(60)` isotope is more dominants. The structure is nearly spherical, like football Sphere is formed by the combination of 20 hexgons and 12 pentagons. Graphite is theromodynamically more stable than all allotropes of carbon. |
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| 618. |
Out of HI and HCl, which is a stronger acid in aqueous solution ? |
| Answer» HI is a stronger acid. | |
| 619. |
Which one of the following arrangements represents the correct order of electron gain enthalpy of the given atomic species?A. `S lt O lt Cl lt F`B. `Cl lt F lt O lt S`C. `O lt S lt F lt Cl`D. `F lt S lt O lt Cl` |
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Answer» Correct Answer - 3 Group `16` and `17` elements all have negative electron gain enthalpies. As we move from Group `16` to Group `17`, it becomes more negative. In Group `16`, it becomes more and more negative as we move down from S, however, O has the least negative `Delta_(eq)H` in the group on account of electron repulsion due to its small size. In Group 17, `Delta_(eg.)H` becomes more and more negative as we move down from `Cl`, however F has less negative `Delta_(eg.)H` due to electron-electron replusion on account of its small size. Thus, the correct order of `Delta_(eg.)H` becoming more and more negative is `O lt S lt F lt Cl` This question can also be credited to Periodic Table (Part 1). |
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| 620. |
White phosphorus exists asA. `P_(8)` moleculesB. `P_(4)` moleculesC. `P_(2)` moleculesD. `P_(6)` molecules |
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Answer» Correct Answer - 2 White phosphorus , a solid at room temperature is soft, waxy and reactive. It exists as tetrahedral `P_(4)` molecules, and the tetrahedral structure remains in the liquid and gaseous state. Above `800^(@)C P_(4)` moleculesin the gas begin to dissocaite into `P_(2)` which have a bond enthalpy of `489.6" kJ mol"^(-1)`. This is only half the value for`N equiv N` because the orbitals in the third shell are much large and give relatively poor `p_(pi)-p_(pi)` overlap. |
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| 621. |
Statement-1: Sodium silicate is called water glass. Statement-2:Salts of lead are poisonous in nature. Statement-3: Producer gas is a mixture of CO and N.A. TTTB. TFTC. FFTD. FTF |
| Answer» Correct Answer - A | |
| 622. |
Which of the following statements is not correct?A. All the oxides of halogens are powerful oxidants.B. The compounds of oxygen and fluorine are not called oxides but fluorides.C. Oxygen fluorides form oxoacids.D. In oxyhalides, bonds are mainly covalent due to small difference in electronegativity of oxygen and halogens. |
| Answer» Correct Answer - C | |
| 623. |
Match the column I with column II and mark the appropriate choice. A. `(A) rarr (iv), (B) rarr (iii), (C) rarr (i), (D) rarr (ii)`B. `(A) rarr (iii), (B) rarr (iv), (C) rarr (i), (D) rarr (ii)`C. `(A) rarr (iv), (B) rarr (i), (C) rarr (ii), (D) rarr (iii)`D. `(A) rarr (ii), (B) rarr (i), (C) rarr (iii), (D) rarr (iv)` |
| Answer» Correct Answer - A | |
| 624. |
Match the column I with column II and mark the appropriate choice. A. `(A) rarr (iv), (B) rarr (i), (C) rarr (iii), (D) rarr (ii)`B. `(A) rarr (ii), (B) rarr (iii), (C) rarr (iv), (D) rarr (i)`C. `(A) rarr (iii), (B) rarr (iv), (C) rarr (ii), (D) rarr (i)`D. `(A) rarr (i), (B) rarr (ii), (C) rarr (iv), (D) rarr (iii)` |
| Answer» Correct Answer - C | |
| 625. |
The following acids have been arranged in order of decreasing acid strength. Identify the correct order. ClOH (I) , BrOH (II) , IOH(III)A. `Igt IIgt III`B. `II gt I gt III`C. `IIIgtIIgtI`D. `I gt III gt II` |
| Answer» Correct Answer - A | |
| 626. |
In which of the following pairs, the two spices are iso-structural?A. `BF_(3)` and `NF_(3)`B. `BrO_(3)^(-)` and `XeO_(3)`C. `SF_(4)` and `XeF_(4)`D. `SO_(3)^(2-)` and `NO_(3)^(-)` |
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Answer» Correct Answer - 2 `|{:("Species","Steric Number","Geometry","Shape"),(BF_(3),3+0,"Trigonal planar","Trigonal planar"),(NF_(3),3+1,"Tetrahedral",underset("pyramidal")("Trigonal")),(BrO_(3)^(-),3+1,"Tetrahedral",underset("pyramidal")("Trigonal")),(XeO_(3),3+1,"Tetrahedral",underset("pyramidal")("Trigonal")),(SF_(4),4+1,underset("bipyramidal")("Trigonal"),"See-Saw"),(XeF_(4),4+2,"Octahedral","Square planar"),(SO_(3)^(2-),3+1,"Tetrahedral",underset("pyramidal")("Trigonal")),(NO_(3)^(-),3+0,"Trigonal planar","Trigonal planar"):}|` This question can also be credited to chemical bonding. |
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| 627. |
Which of the following oxides of nitrogen is a mixed anhydride of two acids?A. `NO_(2)`B. `N_(2)O_(4)`C. both (1) and (2)D. `N_(2)O_(5)` |
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Answer» Correct Answer - 3 Nitrogenn tetroxide and dioxide are in equilibrium with each other: `N_(2)O_(4) hArr 2NO_(2)` The mixture is usually called by the name of the form which predominates at the temperature,neither form is a true peroxide, and it is incorrect to refer to this substance as nitrogen peroxide for that reason. The degree of dissociation is about `20%` at the boiling point, but vapour density measurements show that the proportion of dioxide increases rapidly as the temperature is raised, reaching nearly `100%` at `140^(@)C` . This is also apparent from the change in colour from yellow to dark brown as the temperature rises. At higher temperature further dissociation occurs, which explains why nitrogen dioxide supports the combustion of strongly burning materials: `N_(2)O_(4) hArr underset(at 150^(@)C)underset("complete")(2NO_(2)) hArr 2NO+underset(at 600^(@)C)underset("complete")(O_(2))` The dark colour, which is caused by the `NO_(2)` molecules, is at its deepest at about `150^(@)C` and fades to colourless above `6006(@)C` reappearing on cooling. The arrows stress the reversibility of these changes, which provide good examples of thermal dissociation. The equilibrium mixture of the two oxides is strongly acidic, very soluble in water, forming a mixture of nitrous and nitric acide, of which it the mixed anhydride: `N_(2)O_(4) hArr 2NO_(2) overset(H_(2)O(l))(rarr)HNO_(2)(aq.)+HNO_(3) (aq.)` |
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| 628. |
Which of the following oxides of nitrogen is the anhydride of `HNO_(3)`?A. `N_(2)O_(3)`B. `N_(2)O`C. `NO`D. `N_(2)O_(5)` |
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Answer» Correct Answer - 4 It is an acidic oxide. It reacts with water with hissing sound forming nitric acid: `N_(2)O_(5)+H_(2)Orarr2HNO_(3)` On account of this, it is know as nitric anhydride. With alkalis it forms nitrates: `N_(2)O_(5)+2NaOH rarr 2NaNO_(3)+H_(2)O` |
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| 629. |
In quantitative analysis which of the following groups of metal ions are precipitated as insoluble sulphides when`H_(2)S(g)` is passed through an ammonical solution of the salt mixture?A. `III B`B. `IV`C. `IIA` and `IIB`D. `V` |
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Answer» Correct Answer - 1 The formation of insoluble metal sulphides is quite common in inorganic qualitative analysis. Hydrogen sulphide is bubbled through an acid solution containing unknown metal ions. The presence of the high hydrogen ion concentration reduces the sulphide ion concentration to extremely low levels: `H_(2)S(aq.)+2H_(2)O(l) hArr 2H_(3)O^(+)(aq.)+S^(2-) (aq.)` This very low level of sulphide ion is still enough to precipitate the most insoluble metal sulphides, those with a solubility product `K_(sp)` smaller than`10^(-30)`. These metal sulphides are separated by filtration or centrifugation. The pH of the filtrate is increased by adding base. This increase shifts the sulphide equilibrium to the right, thereby raising the concentretion of sulphide ions to the point where those metal sulphide with a solubility product between `10^(-20)` and `10^(-30)` (mainly the transition metals of period 4) precipitate `IIA` and `IIB`. groups of metal ions are precipitated as insoluble sulphides when `H_(2)S` is passed through a weakly acidified solution of the salt mixture whilst `III` B group of metal ions are separated as insoluble sulphides when `H_(2)S` is passed through an ammoniacal solution of the salt mixture. Specific tests could then be used to identify which metal ions are present. More recently, thio- acetamide, a reagent that hydrolyzes to hydrogen sulphide, has been used for such tests. In addition to forming conventional sulphides, some elements form disulphides,`S_(2)^(2-)` ions analogous to dioxide`(2-)`. Thus, `FeS_(2)` does not contain iron in a high oxidation state, but the disulphide ion and `Fe^(2+)`. Also the alkali and alkaline earth metals form polysulphides, which contain the `S_(n)^(2-)` ion, where n has value between 2 and 6. |
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| 630. |
Knowing the electron gain enthalpy values for ` O to O^(-) " and " O to O^(2-) " as " -141 " kJ mol"^(-1) " and " 702 " kJ mol"^(-1)` respectively, how can you account for the formation of a large number of oxides having `O^(2-)` species and not `O^(-)` ? |
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Answer» According to available data : `O +e^(-) to O^(-) , Delta_(eg) (H)=-141 " kJ mol"^(-1)` ` O=2e^(-) to O^(2-) , Delta_(eg) H=+ 702 " kJ mol"^(-1)` Although the formation of divalent anion `(O^(2-))` needs more energy as compared to monovalent anion `(O^(-))` where energy is actually released, still in large number of oxides (e.g., `Na_(2)O, K_(2)O, CaO` etc.) oygen is divalent in nature. This is on account of a more stable crystal lattice because of greater magnitude of electrostatic forces of attraction involving divalent oxygen than the oxides in which oxygen is monovalent in nature. |
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| 631. |
`H_(2)S` can formA. four series of saltB. two series of saltC. only one series of saltsD. three series of salt |
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Answer» Correct Answer - 2 Hydrogen sulphide has no effect on dry litmus paper but once the litmus paper becomes wet it will turn blue litmus paper a wine-red colour, showing that it functions as a weak acid in solution. `H_(2)S` is very weak dibasic acid.It ionization in water takes place in two stages, the second one occuring only to a very minute extent: `H_(2)S(aq.)+H_(2)O(l) hArr H_(3)O^(+)(aq.)+HS^(-)(aq.)` `HS^(-)(aq.)+H_(2)O(l) hArr H_(2)O^(+))aq.)+S^(2-)(aq.)` In the presence of hydroxyl ions (a much stronger proton acceptor than water molecules ,the ionisation of hydrogen sulphide is much more extensive. Most metal sulphides can be regarded as salts of `H_(2)S`. Since it is dibasic two series of salts can be drived from it .The hydrogen sulphides and normal sulphides (or just sulphides). For example ,the reaction with sodium hydroxide solution produces the hydrogen sulphide and sulphide,i.e.,`Na^(+)HS^(-)` and`(Na^(+))_(2)S^(2-)` `H_(2)S(aq.)+Na^(+)OH^(-)(aq.)rarrNa^(+)HS^(-)(aq.)+H_(2)O(l)` `Na^(+)Hs^(-)(aq.)+Na^(+)OH^(-)(aq.)rarr(Na^(+))_(2)S^(2-)(aq.)+H_(2)O(l)` The reaction do not go to completion, i.e, the alkali metal hydrosulphides and sulphides show an alkaline reaction in solution.thsu demonstrating presence of `OH^(-)(aq.)` ions. |
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| 632. |
Which of the following is incorret about hydrogen sulphide?A. it is a coloured gas with the smell of rotton eggsB. it Is very poisonousC. it is sligtly heavier than air and fairly solublein waterD. its molecules is `V`-shaped |
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Answer» Correct Answer - 1 It is a colourless gas.It is an extremely poisonous substance (a slittle as`1` part per `1000` parts of air is fatal),but fortunately its smell becomes introerable long before the total concentration is reached. Unlike water `H_(2)S` is a gas,since the electronegativity of the`S` atom is insufficient to allow it to participate in intermolecular hydrogen bonding. However,its molecules like `H_(2)O` is angular with two lone pairs and two bonding pairs. |
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| 633. |
Which of the following is incorret regarding sulphur dioxide?A. it is a coloured ,poisionous gas with a very pungant suffoacting odour.B. it is a heavier than airC. it is almost insoluble in waterD. it can be easily liquefied to a colorless liquid at `-10^(@)C` and into a snowlike solids at `-76^(@)C` |
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Answer» Correct Answer - 3 `SO_(2)` is very soluble in water but like ammonia and carbon-dioxide almost all the dissovled gas is present as the sulphur dioxide molecules, only a very small proportions forms sulphurous acid. |
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| 634. |
`CO_(2)` is a linear, monomeric covalent compound. Its real structure is a resonance hybrid of _____resonance structures.A. twoB. fourC. threeD. it does not exhibit resonance |
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Answer» Correct Answer - C `CO_(2)` molecule is mostly described as `:overset(..)(O)=C=overset(..)(O):` This structure predicts that `CO_(2)` is linear and both `C-O` bonds should have the same length `(122 p m)`. Experimentally, both `C-O` bonds are found to be `115` pm indicating some triple bond character. This can be justified if `CO_(2)` is considered to be a resonance hybrid of three resonance forms: `overset(-):overset(..)underset(..)(O)-C-=O:^(+) harr :overset(..)(O)=C=overset(..)(O):harr:overset(+)(O)-=C-underset(..)overset(..)Ooverset(-):` In addition to `sigma` bonds between `C` and `O`, there is a three-center four-electron `pi` bond covering all three atoms. |
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| 635. |
In aqueous solution, almost all the carbon dioxide is present asA. `CO_(2)(aq)`B. `H_(2)CO_(3)`C. `HCO_(3)^(-)`D. `CO_(3)^(2-)` |
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Answer» Correct Answer - A When `CO_(2)` dissolves in water, only some of the molecules react with water to form corbonic acid, `H_(2)CO_(3)`, which has recently been isolated at low temperature and in the absence of water. In the presence of water, dissociation to carbon dioxide and water occurs rapidly. Carbonic acid is an extremely weak diprotic (dibasic) acid, as can be seen from the `pK_(a)` values corresponding to each of the ionization steps: `CO_(2)(g)+H_(2)O(l)hArrH_(2)CO_(3)(aq.)` `H_(2)CO_(3)(aq.)+H_(2)O(l) hArr H_(3)O^(+)(aq.)+HCO_(3)^(-)(aq.),pK_(a1) = 6.37` `HCO_(3)^(-)(aq.)+H_(2)O(l) hArr H_(3)O^(+)(aq.)+CO_(3)^(2-)(aq.),pK_(a2)=10.33` Thus, a solution of `CO_(2)` in water is actually an equilibrium mixture of `CO_(2)`, `H_(2)CO_(3)^(-)`, and `CO_(3)^(2-)` . `CO_(2)` is only slightly hydrated to `H_(2)CO_(3)`, and the solution contains few carbonates or bicarbonate ions., Most of the dissolved `CO_(2)` remains loosely hydrated to give `CO_(2) (aq)`. |
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| 636. |
(i) white phosphorus (ii) red phosporus and (iii) balck phosphorus. Write the difference between white red and black phosphorus on the basis of their structure and reactivity. Phosphorus has three allotropic forms __ |
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Answer» Difference on the basis of structure (i) White phosphorus exists as discrete tetrahedral molecules. Its structure is tetrahedral with six P-P bonds. (ii) Red phosphorus has polymeric structure in which `P_(4)` tetrahedra are linked to each other through P-P bonds resulting in a chain. Difference on the basis of reactivity White phosphorus is much more reactive as compared to red phosphorus. Its ignition temperature (303 K) is quite low as compared to that of red phosphorus (543 K) |
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| 637. |
Which of the following metals continue to burn in the atmosphere of `CO_(2)` ? (i) `Na` (ii) `K` (iii) `Mg` (iv) `Ca`A. (i), (ii)B. (iii), (iv)C. (i), (ii), (iii), (iv)D. (ii), (iii), (iv) |
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Answer» Correct Answer - C Certain active metals such as `Na, K, Mg`, and `Ca` continue to burn in the atmosphere of `CO_(2)` as they extract oxygen from it, i.e., `CO_(2)` reacts with burning metal: `2Ca(s) + CO_(2)(g) overset(Delta)rarr 2CaO(s) + C(s)` |
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| 638. |
Sulphur dioxide neither burns nor it helps in burning. However, burning -continue to burn in its atmosphere.A. `Mg`B. `K`C. `Cu`D. Both (1) and (2) |
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Answer» Correct Answer - 4 `3Mg+SO_(2)rarr2MgO+MgS` `4K+3SO_(2)rarrK_(2)SO_(3)+K_(2)S_(2)O_(3)` |
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| 639. |
Why does burning Mg continue to burn in a jar containing NO but burning S gets extinguished ? |
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Answer» Magnesium is a strong reducing agent and reduces NO to form `Mg_(3)N_(2)`. The reaction is highly exothermic and NO decomposes to `N_(2) " and " O_(2)`. `5Mg+2NOto 2MgO+underset("Mag. Nitride")(Mg_(3)N_(2)+heat` `2NOoverset("heat")to N_(2)+O_(2)` Oxygen keeps the magnesium ribbon burning. On the other hand, sulphur is a non-metal and acts as an oxidising agent and cannot reduce NO. Heat produced as a result of burning sulphur is not sufficient to decompose NO to `O_(2)`. Therefore, burning sulphur gets extinguished. |
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| 640. |
Bond dissociation enthalpy of E-H (E=element) bond is given below. Which of the following compounds will act as strongest reducing agent?A. `NH_(3)`B. `PH_(3)`C. `AsH_(3)`D. `SbH_(3)` |
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Answer» Correct Answer - D `SbH_(3)` will act as strongest reducing agent as it has lowest bond dissociation energy and Sb-H bond is weaker. |
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| 641. |
Some of the properties of the two species, `NO_(3)^(-)` and `H_(3)O^(+)` are described below.Which one of them is correct?A. Dismilar in hybridization for the centeral atom with different structuresB. Isostructural with same hybridization for the central atomC. Isostructural with different hybridization for the centeral atomD. Similar in hybridization for the central atom with different structures |
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Answer» Correct Answer - 1 `{:("Species","Steric Number","Hybridization","Geometry"),(NO_(3)^(-),3+0,sp^(2),"Trigonal planar"),(H_(3)O^(+),3+1,sp^(3),"Tetrahedral with one position "),(,,,"occupied by a long pair."):}` this questio can be credited to chemical bonding. |
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| 642. |
In the case of alkali metals, the covalent character decreases in the order.A. `MF gt MCl gt MBr gt MI`B. `MF gt MCl gt MI gt MBr`C. `Ml gt MBr gt MCl gt MF`D. `MCl gt MI gt MBr gt MF` |
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Answer» Correct Answer - 3 Covalent character of metal halides decreases (and hence ionic character increases) as the electronegativity of the halogen increases from `I` to `F`. |
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| 643. |
Which of the following molecules acts as a Lewis acid?A. `(CH_(3))_(2)O`B. `(CH_(3))_(3)P`C. `(CH_(3))_(3)N`D. `(CH_(3))_(3)B` |
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Answer» Correct Answer - 4 Lewis acid is the one which can accept an electron pair due to the presence of an atom which either has incomplete octet like B or can expand its octet like S. |
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| 644. |
Out of `O_(2) " and " O_(3)` which is a better oxidising agent ? |
| Answer» Correct Answer - Ozone | |
| 645. |
What is the shape of ozone molecule ? |
| Answer» Correct Answer - Bent or angular | |
| 646. |
Ozone is used as a`//`anA. bleaching agentB. oxidizing agentC. deisnfectantD. All of these |
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Answer» Correct Answer - 4 It is used for bleaching oils ,flour,ivory ,wax, starch and delicate fabrics,Due to the ease with which it liberates atoms of nascent oxygen `(O_(3)rarrO_(2)+O)`, it acts as a powerful oxidizing agent: `2NO_(2)+O_(3)rarrN_(2)O_(5)+O_(2)` In most of the reactions,`O_(2)` is evolved but there are two reactions in which whole of the oxygen is used up in the process of oxidation: `3SO_(2)+O_(3)rarr3SO_(3)` `3SnCl_(2)+6HCl+O_(3)rarr3SnCl_(4)+3H_(2)O` Ozone is used as a disinfectant.For example ,it is used to purify drinking water ,since it destroys bacteria and viruses. Its advantage over `Cl_(2)` for this purpose is that it avoids the unpleasant smell and taste of `Cl_(2)` ,since any excess `O_(3)` soon decomposes to `O_(2)`. For similar reasons it is used to treat water in swimming pools. |
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| 647. |
The amount ozone in a gas mixture may be determined by passing the gas into a `"_____"` solution buffered with a borate buffer (pH 9.2).A. `KI_(3)`B. `KIO_(3)`C. `KI`D. `KIO_(4)` |
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Answer» Correct Answer - 3 When ozone reacts with an excess of potassium iodide solution buffered with a borate buffer (`pH9.2)`, iodine is liberated which can be titrated against a standard solution of sodium thiosulphate: `O_(3)+2K^(+)+2I^(-)+H_(2)O rarr I_(2)+2KOH+O_(2)` This is a quantitative method for estimating `O_(3)` gas. |
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| 648. |
Write balanced equation for reaction of `XeF_(4)` with water. Also name the reaction. |
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Answer» `3XeF_(4)+6H_(2)O to 2Xe+XeO_(3)+12HF+(3)/(2) O_(2)`. It is a disproportionation reaction. |
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| 649. |
`PH_(3)` forms bubbles when passed slowly in water but `NH_(3)` dissolves. Explain why ? |
| Answer» `PH_(3)` does not dissolve in water due to lack of intermolecular hydrogen bonding. Ammonia on the other hand is highly soluble in water since molecules of ammonia and water are involved in intermolecular hydrogen bonding. | |
| 650. |
In qualitative analysis when `H_(2)S` is passed through an aqueous solution of salt acidified with dil. HCl, a black precipitate is obtained. On boiling the precipitate with dil. `HNO_(3)`, it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution givesA. deep blue precipitate of `Cu(OH)_(2)`B. deep blue solution of `[Cu(NH_(3))_(4)]^(2+)`C. deep blue solution of `Cu(NO_(3))_(2)`D. deep blue solution of `Cu(OH)_(2).Cu(NO_(3))_(2)` |
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Answer» Correct Answer - B `CuSO_(4)+H_(2)Soverset("dil. HCl")rarrunderset("Black ppt.")(CuSdarr)+H_(2)SO_(4)` `CuS+2HNO_(3"(dil.)")overset(Delta)rarrunderset("Blue solution")(Cu(NO_(3))_(2))+H_(2)S` `Cu(NO_(3))_(2)+4NH_(3)rarrunderset ("Deep blue solution")([Cu(NH_(3))_(4)]^(2+))+2NO_(3)^(-)` |
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